Notice of Retraction: Effect of Temperature Shock on Organisms in EBPR Reactors under Low Temperature

Abstract

A laboratory-scale anaerobic/aerobic sequencing batch reactor (SBR) as models for enhance biological phosphorus removal (EBPR) processes was used to study the effect of temperature shock on reactor performance and microbial population structure dynamics. SBR fed with acetate as the carbon source were operated for 34 days. The original temperature in SBR was 8 °C. A temperature shock was carried out in reactor. The temperature in 12d~19d increased to 30 °C±2 °C and in 20d~34d decreased to 8 °C±2 °C. The microbial community structure was analyzed by fluorescent in situ hybridization (FISH). TFOs-like shape of phosphorus accumulating organisms (PAOs) was observed when temperature rose to 30 °C. But the shape of PAOs restored to dense cluster when temperature dropped from 30 °C to 8 °C. PAOs stopped absorb substrate under anaerobic phase on 12d when temperature rose to 30 °C. Meanwhile, COD and phosphate removal efficiency was worse in 12d~19d and the amount of PAOs or glycogen accumulating organisms (GAOs) decreased on 19d. This condition showed that temperature shock could disturb organisms' metabolism. The average of phosphate removal rate was 49.11% in 20d~34d and was higher than it in 0d~11d (was 23.84%). COD removal rate in 20d~34d was the same as it was in 0d~11d. This result indicated that phosphate removal efficiency improved through temperature shock. PAOs were dominant organism in sludge through temperature shock. GAOs from Alphaproteobacteria were eliminated and GAOs from Gammaproteobacteria survived.